cdfspeed: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/cdfspeed - from package: cdftools

You may install the required package with command apt-get install {package}

Error in other languages:
cdfspeed: bevel nie gevind nie
cdfspeed: comandă negăsită
cdfspeed: comando não encontrado
cdfspeed: commande introuvable
cdfspeed: command not found
cdfspeed: käsku ei ole
cdfspeed: không tìm thấy lệnh
cdfspeed: komanda nerasta
cdfspeed: Kommando nicht gefunden.
cdfspeed: kommandot finns inte
cdfspeed: komut yok
cdfspeed: nie znaleziono polecenia
cdfspeed: níor aimsíodh an t-ordú
cdfspeed: no se encontró la orden
cdfspeed: no s'ha trobat l'ordre
cdfspeed: opdracht niet gevonden
cdfspeed: parancs nem található
cdfspeed: perintah tidak ditemukan
cdfspeed: príkaz nenájdený
cdfspeed: příkaz nenalezen
cdfspeed: команда не найдена
cdfspeed: командата не е открита
cdfspeed: 命令找不到
cdfspeed: コマンドが見つかりません